Cam shaft drive assembly



United States Patent iitice 333,933 Patented Mar. 21, 1967 3,309,933 CAMSHAFT DRIVE ASSEMBLY Sheldon Lee Pastor, St. Paul, Minn., and Rudolph A.

Rom, Naperville, .and Ivyron Zarr, Chicago, lil., assignors to Minnesotall/Iining and Manufacturing Company, St. Paul, Minn., a corporation ofBeiaware Original application lviay 8, 1961, Ser. No. 163,352, nowPatent No. 3,149,797, dated Sept. 22, 1964. Divided and this application.'Iuiy 13, 1964, Ser. No. 332,199

Claims. (Cl. 74-125) rThis application is a division of application Ser.No. 108,352, filed May S, 1961, now Patent No. 3,149,797, forSelf-Hireading Magnetic Tape Recording and Reproducing Apparatus.

This invention relates to improvements in sequential driving mechanismsand in one aspect relates to a sequential drive mechanism for a camshaft to effect rotation thereof at prescribed intervals throughsuccessive rotational steps each being less than one completerevolution.

The present invention provides an improved driving and control mechanismfor edecting the sequential operation of numerous elements including asingle cam shaft having numerous cams thereon engaging cooperating camIfollowers.

The present invention is adapted for use with an improvedrecorder-reproduced as described in the above referred to applicationand provides an improved driving and timing mechanism for effecting theoperational sequences in the proper timed relationship.

The advantages of the present invention will become more apparent as thedetailed description proceeds, reference being had to the accompanyingdrawing which forms a part of this specification, wherein:

FIGURE 1 is a side elevation View of the drive mechanism and cam shaft;

FIGURE 2 is a fragmentary sectional plan view taken approximately alongthe line II-II of FIGURE 1; and

FIGURES 3 and 4 are plan views illustrating certain cam profiles.

The drive mechanism of the present invention is adapted to drive a camshaft 222 which is supported -by suitable bearings 4 and 5 fixed in anupper deck or frame member 2 and a lower deck or frame member 3,respectively. Power for operation of the mechanism is derived from anelectric motor 8, illustrated in FIGURE 2, which is supported by thelower deck 3 and which has an upstanding drive shaft 10. A drive roller11 is secured to the shaft 1G and drivingly engages a suitably mountedidler drive wheel 17 which in turn affords continuous driving engagementbetween the motor drive shaft 1G and a liywheel 14. 'Ihe liywheel 14 isfixed on a drive shaft or cam shaft 13 which is suitably journalled inthe decks 2 and 3. The drive shaft 13 is the driving member for thenovel cam shaft drive mechanism and is formed with a knurled portion 15above the deck 3 yand below the flywheel 24.

In an apparatus where itis desirous to perform various operative stepsor work functions through the use of levers in a timed or sequentialrelationship, such may be accomplished by means of cams having variousprofiles. In the illustrated embodiment of the present invention severalcams 219, 22), 221, 224 and 225 yare provided upon the cam shaft 222.These cams serve to produce Jork functions through cooperating camfollower rollers such as rollers 125 and 161, illustrated in FIGURES 1,3 and 4. The cam follower rollers 125 and 161 are supported by suitablelevers 124 and 160 which may in turn be pivoted on the upper deck 2 andwhich have suitable means on the opposite end portions thereof forperforming the desired work function. Similar cam followers may engagethe cams 221, 224 and 225 but are not shown.

It is to be understood however that additional cams as desired may beincluded `on the shaft 222.

In the illustrated embodiment the cam shaft 222 is rotated clockwise insteps or increments of 36, which increments are numbered from 1 to 10 inFIGURES 3 and 4. The actuating means for the shaft 222 comprises aone-way ratchet dog clutch below the deck 3 having a lower member 226fixed to the cam shaft 222 and having upwardly facing inclined teeth asthus shown in FIG- URE 1. The upper clutch member 227 complemental tothe lower member 226 oats on the cam shaft 222 and is provided with anintegral arm 228 which carries an upstanding pin 229 which projectsupward through a suitable slot in the deck 3. A ratchet Wheel 230 is xedon the cam shaft 222 Ibelow the cam 223, and a pawl 231 pivoted at 232and biased in a clockwise direction 4by a spring 233 into engagementwith the lratchet 230 prevents counterclockwise rotation of said ratchetwheel, the shaft 222 and the cams fixed thereto.

Fixed on the cam shaft 222 between the decks 2 and 3 is an indexing cam234. Overlying the deck 3 is a generally T-shaped lever `arm 235 mountedfor horizontal swinging movement about a pivot 236. The member 235 isformed with a slot 237 for accommodating the upstanding ratchet arm pin229, said member also carrying an opstanding stub shaft 238. Freelyrotatable on the stub shaft 238 is an eccentric circular cam 239 whichis formed 4with a peripheral groove to accommodate a rubber-like O ringor tire member 240. A tension spring 241 is suitably anchored at one endand has its other end attached to the member 235 to bias the latter in aclockwise direction and thereby bias the cam 239 into engagement withthe knurled portion 15 (FIGURE 2) of the drive shaft 13.

Referring again to FIGURES 1 and 2, a lever 242 has' a channel-shapedend portion 243 and is pivotally mounted on a fixed pin 244. The otherend of the lever 242 carries an upstanding pin 245. A generally V-shapedlink 246 is formed with a slot 247 adjacent its apex for accommodatingthe pin 24,5. One arm of the link 246 is pivotally connected to themember 235 as by pin 248, and the other arm of said link carries anupstanding cylindrical cam follower 249. A tension spring 250 connectsthe member 235 and link 246 as shown in FIGURE 2. Suitably mounted onthe deck 3 is the solenoid 251 having a plunger 252 engageable with thevertical wall of the channel-shaped portion 243 of lever 242, saidsolenoid being effective when energized to project the plunger 252 fromits retracted position wherein the end portion thereof engages the leverportion 243 at the dot and dash line position of the lever shown inFIG-URE 2 to the projected position of said plunger shown in FIGURE 2.

The indexing cam 2312. is of circular configuration, See FIGURE 2,except for cut-away peripheral portions 253 and 254, and the camfollower 249 is adapted to coact with said cam. The clockwise rotationof the drive shaft 13 causes counterclockwise rotation of the cam 239held in Contact therewith by the spring 241, and such rotation of thecam 239 causes oscillation or swinging movement of the member 235between the solid line and the dot and dash line positions thereof shownin FIGURE 2. Such oscillatory movement continues -so long as the cam 239remains in driving engagement with the drive shaft 13. Movement of themember 235 toward its dot and dash line position causes movement of theratchet arm pin 229 therewith and clockwise rotation of the upperratchet member 227 through an angle of 36 to effect like rotation of thecam shaft 222 and all of the cams fixed thereto. Return movement of themember 235 toward its solid line position returns the upper ratchetmember 227 to its initial position for reengagement of its teeth withthose of the lower ratchet member 226.

Movement of the member 235 toward its dot and dash line retractedposition pulls the cam follower 249 on link 246 into engagement with theperiphery of the indexing cam 234, and if neither of the cut-outportions 253 and 254 is presented to said follower, the oscillation ofthe member 235 continues. If, however, a cutout portion 253 or 254 ispresented to the follower 249 when the member 235 approaches the dot anddash line position thereof, said follower moves into the presentedcut-out portion to the dot .and dash line position shown in FIGURE 2.Such movement of the follower 249 permits the pin 245 to move toover-center position with respect to a line connecting the pins 244 and248, and the toggle provided by the link 246 and lever 242 is held inthe over-center dot and dash line position shown in FIGURE 2 by the biasof the springs 241 and 25@ forming holding means for the member 235 whenin its retracted position. With the toggle in over-center position themember 235 is prevented from returning from its dot and dash lineposition, and the cam roller 24) rotates out of engagement with thedrive shaft 13. The parts of the actuating mechanism for cam shaft 222remain stationary until the solenoid 251 is subsequently energized toproject the plunger 252 against the wall of the portion 243 of the lever242 and pivot said lever counterclockvvise from its dot and dash lineposition sufficiently to return the pin 245 over-center. This breaks thetoggle and permits the spring 241 to again pull the cam roller 239 intodriving engagement with the drive shaft 13 to thereupon initiate anothercycle of oscillation.

It is to be understood that the cut-away portions 253 and 254 may havevarying shapes or the indexing cam 234 may include additional cut-awayportions to interrupt the timed rotation of the cam shaft 222 atintervals as desired. Control of the incremental drive for cam 'shaft222 is thus provided by the indexing cam 234, the solenoid 251 andplunger 252.

Energization of the solenoid 251 will be in response to tbe closing ofone or more switches, not shown, included in the apparatus to which theillustrated drive mechanism forms a part.

Having thus described one specific embodiment of the invention it is tobe understood that various changes and vmodifications may be madetherein without departing from the spirit of the invention, and all suchchanges are contemplated as may come within the scope of the appendedclaims.

What is claimed is:

1. In combination, a drive shaft, an arm mounted for pivotal movement onan axis parallel with that of said drive shaft, an eccentric circularcam mounted on said `arm for rotation on an axis parallel with that ofsaid drive shaft,` means biasing said cam toward engagement with saiddrive shaft, rotation of said drive shaft while said cam is engagedtherewith effecting rotation of said cam and oscillatory movement ofsaid arm, a cam shaft, a driving connection for effecting rotation ofsaid cam shaft in response to oscillatory movement of said arm, saiddriving connection comprising a single direction clutch having anoscillatable first member connected to said arm, and va cooperatingsecond member fixed to said cam shaft, releasable holding meansassociated with said arm for holding the latter substantially in itsretracted position farthest from said drive shaft when moved to saidretracted position, and control means including an indexing cam carriedby said cam shaft for engagement by said holding means for renderingsaid holding means operative or inoperative to hold the arm retractedwhen said cam shaft reaches preselected positions.

2. In combination, Ia drive shaft, an arm mounted for pivotal movementon an axis parallel with that of said drive shaft, an eccentric circularcam mounted on said arm for rotation on an axis parallel with that ofsaid drive shaft, means biasing said cam toward engagement with saiddrive shaft, rotation of said drive shaft while said cam is engagedtherewith effecting rotation of said cam and oscillatory movement ofsaid arm, a cam shaft, a driving connection for effecting rotation ofsaid cam shaft in response to oscillatory movement of said arm, saiddriving connection comprising a single direction clutch having anoscillatable first member connected to said arm, and a cooperatingsecond member fixed to said cam shaft, releasable holding means`associated with said arm for holding the latter substantially in itsretracted position farthest from said drive shaft when moved to saidretracted position, control means including `an indexing cam mounted onsaid cam shaft for engagement with said holding means, said indexing camhaving at least one first position in which said control means renderssaid holding means inoperative 'and at least on-e second position inwhich said control means permits said holding means to operate, andmeans for releasing said holding means while said indexing cam is in itssecond position and said holding means is holding said arm in retractedposition.

3. In combination, a drive shaft, an arm mounted for pivotal movement onan axis parallel with that of said drive shaft, an eccentric circularcam mounted on said arm for rotation on an axis parallel with that ofsaid drive shaft, means biasing said cam toward engagement with saiddrive shaft, rotation of said drive shaft while said cam is engagedtherewith effecting rotation of said cam and oscillatory movement ofsaid arm, a cam shaft, a driving connection -ffor effecting rotation ofsaid cam shaft in response to oscillatory movement of said arm, saiddriving connection comprising a single direction clutch having anoscillatable first member connected to said arm, and a cooperatingsecond member fixed to said cam shaft, releasable holding meanscomprising a toggle linkage associated with said arm and normallymovable to an over-center holding position on movement of said armsubstantially to its retracted position farthest from said drive shaft,and control means including an indexing cam adapted for engagement withsaid toggle linkage, said indexing cam having at least one firstposition in which said control means prevents movement of said linkageto said over-center holding position, said indexing cam also having atleast one second position in which said control means permits movementof said linkage to said over-center holding position wherein it holdssaid arm in substantially said retracted position.

4. In combination, a drive shaft, an arm mounted for pivotal movement onan axis parallel with that of said drive shaft, an eccentric circularcam mounted on said arm for rotation on an axis parallel with that ofsaid drive shaft, means biasing said cam toward engagement with saiddrive shaft, rotation of said drive shaft while said cam is engagedtherewith effecting rotation of said cam and oscillatory movement ofsaid arm, a cam shaft, a driving connection for effecting rotation ofsaid cam shaft in response to oscillatory movement of said arm, saiddriving connection comprising a single direction clutch having anoscillatable first member connected to said arm, and a cooperatingsecond member fixed to said cam shaft, releasable holding meanscomprising a toggle linkage associated with said arm and normallymovable to an over-center holding position on movement of said armsubstantially to its retracted position farthest from said drive shaft,control means including an indexing cam carried by said cam shaft forengagement with a yfollower on said toggle linkage, said indexing camhaving at least one first position in which said control means preventsmovement of said linkage to said over-center holding position, saidindexing -cam also having at least one second position in which saidcontrol means permits movement of said linkage to said overcenterholding position wherein it holds said arm in substantially saidretracted position, and electroresponsive actuating means adapted forengagement with said toggle linkage for effecting return movement ofsaid toggle linkage when it is in its over-center position, therebyreleasing said arm for advancing movement toward said drive shaft.

S. In combination, a drive shaft, an arm mounted -for pivotal movementon an axis parallel with that of said drive shaft, an eccentric circularrcam mounted on said arm for rotation on an axis parallel with that ofsaid drive shaft, means biasing said cam toward engagement with saiddrive shaft, rotation of said drive sha-ft while said cam is engagedtherewith effecting rotation of said cam and oscillatory movement ofsaid arm, a cam shaft, a driving connection for eifecting rotation ofsaid cam shaft in response to oscillatory movement of said arm, saiddriving connection comprising a single direction clutch having anoscillatable first member connected to said arm, and a cooperatingsecond member fixed to said cam shaft, releasable holding meanscomprising a toggle linkage associated with said arm and normallymovable to an over-center holding position on movement of said armsubstantially to its retracted position lfarthest from said drive shaft,control means including an indexing cam driven by said cam shaft andpositioned for engagement with said toggle linkage, said indexing camhaving at least one rst position in which said control means preventsmovement of said linkage to said over-center holding position, said camalso having at least one second position in which said control meanspermits movement of said linkage to said over-center holding positionwherein it holds said arm in substantially said retracted position, andelectroresponsive actuating means adapted for engagement with saidtoggle linkage for eifecting return movement of said toggle linkage whenit is in its over-center position, thereby releasing said arm foradvancing movement toward said drive shaft.

References Cited by the Examiner UNITED STATES PATENTS 1,155,459 10/1915Woodward 74-125 1,565,601 12/1925 Swanson 74-124 1,568,430 1/1926 Uhl74-25 1,758,730 5/1930 Winters 74-45 2,128,413 8/1938 Hejduk et al.74-124 X MILTON KAUFMAN, Primary Examiner.

FRED C. MATTERN, Examiner.

D. H. THIEL, Assistant Examiner.

1. IN COMBINATION, A DRIVE SHAFT, AN ARM MOUNTED FOR PIVOTAL MOVEMENT ONAN AXIS PARALLEL WITH THAT OF SAID DRIVE SHAFT, AN ECCENTRIC CIRCULARCAM MOUNTED ON SAID ARM FOR ROTATION ON AN AXIS PARALLEL WITH THAT OFSAID DRIVE SHAFT, MEANS BIASING SAID CAM TOWARD ENGAGEMENT WITH SAIDDRIVE SHAFT, ROTATION OF SAID DRIVE SHAFT WHILE SAID CAM IS ENGAGEDTHEREWITH EFFECTING ROTATION OF SAID CAM AND OSCILLATORY MOVEMENT OFSAID ARM, A CAM SHAFT, A DRIVING CONNECTION FOR EFFECTING ROTATION OFSAID CAM SHAFT IN RESPONSE TO OSCILLATORY MOVEMENT OF SAID ARM, SAIDDRIVING CONNECTION COMPRISING A SINGLE DIRECTION CLUTCH HAVING ANOSCILLATABLE FIRST MEMBER CONNECTED TO SAID ARM, AND A COOPERATINGSECOND MEMBER FIXED TO SAID CAM SHAFT, RELEASABLE HOLDING MEANSASSOCIATED WITH SAID ARM FOR HOLDING THE LATTER SUBSTANTIALLY IN ITSRETRACTED POSITION FARTHEST FROM SAID DRIVE SHAFT WHEN MOVED TO SAIDRETRACTED POSITION , AND CONTROL MEANS INCLUDING AN INDEXING CAM CARRIEDBY SAID CAM SHAFT FOR ENGAGEMENT BY SAID HOLDING MEANS FOR RENDERINGSAID HOLDING MEANS OPERATIVE OR INOPERATIVE TO HOLD THE ARM RETRACTEDWHEN SAID CAM SHAFT REACHES PRESELECTED POSITIONS.